I. Field of the Invention
This invention is in the field of preparing higher order cuprate complexes from alkyl, vinyl, benzyl, phenyl or allyl stannane compounds which complexes are useful as reactive intermediates in organic synthesis. In particular the process and compounds of this invention are useful for the addition of the omega chain to cyclopentenones in the synthesis of prostaglandins.
II. Prior Art
The state of the art of higher order cuprate complexes is summarized in Synthesis, #4, p. 325, (1987) where higher order cuprate complexes of the formulae R.sub.t RCu(CN)Li.sub.2, R.sub.t Cu(2-thienyl)CNLi.sub.2, and R.sub.t RCu(SCN)Li.sub.2 and their use are disclosed. R.sub.t represents the group transferred to an organic compound to form a carbon to carbon bond in a subsequent reaction with the complex.
U.S. Pat. No. 4,499,296 describes the preparation of a large number of prostaglandins prepared by the sequence of reactions set out in the following steps:
(i) a stannane compound of the formula ##STR1## is reacted with alkyl lithium in one reaction vessel; (ii) an organo copper compound is formed in a separate vessel; PA0 (iii) the reagents formed in (i) and (ii) are mixed together and added to a cyclopentenone: ##STR2## to provide prostaglandins of formula I ##STR3## wherein, R"' is --CO.sub.2 R"";
R"" is hydrogen or lower alkyl containing 1 to 6 carbon atoms; PA1 R' is lower alkyl containing 1 to 6 carbon atoms, vinyl or ethynyl; PA1 R" is alkyl or cycloalkyl containing 3 to 5 carbon atoms; and PA1 the wave line represents R,S stereochemistry. PA1 (b) each R is independently lower alkyl, alkenyl, phenyl, naphthyl, phenanthryl, or thienyl, provided that (i) each of the aforementioned radicals may be substituted with non-interfering substituents and (ii) only one R in the first cuprate complex may be alkenyl, phenyl, naphthyl, phenanthryl, or thienyl; and PA1 (c) each R.sup.1 is independently lower alkyl; PA1 wherein R.sub.t is a carbanion for carbon to carbon bond formation reactions and is not the same as any R in the first cuprate complex and each R.sup.2 is independently lower alkyl or R.sub.t ; PA1 (b) each R is independently lower alkyl, alkenyl, phenyl, naphthyl, phenanthryl, or thienyl, provided that (i) each of aforementioned radicals may be substituted with non-interfering substituents and (ii) only one R in the first cuprate complex may be alkenyl, phenyl, naphthyl, phenanthryl, or thienyl; and PA1 (c) each R.sup.1 is independently lower alkyl; PA1 wherein R.sub.t is a carbanion for carbon to carbon bond formation reactions and is not the same as any R in the first cuprate complex and each R.sup.2 is independently lower alkyl or R.sub.t ;
JACS 94 7210 (1972) describes lithium copper vinyl complexes. Prostaglandin Synthesis, Academic Press, 1977, Chapt. 7 describes prostaglandin synthesis generally. U.S. Pat. Nos. 4,449,296; 4,322,543; 4,578,505; and 4,271,314 describe organotin intermediates in the preparation of prostaglandins.